/*
 * This computer program is the confidential information and proprietary trade
 * secret of Apptonelabs, Inc. Possessions and use of this program must
 * conform strictly to the license agreement between the user and
 * Apptonelabs, Inc., and receipt or possession does not convey any rights
 * to divulge, reproduce, or allow others to use this program without specific
 * written authorization of Apptonelabs, Inc.
 * 
 * Copyright (c) 2012-2015 Apptonelabs, Inc. All Rights Reserved.
 */
package com.apptonelabs.vnc.vphone;

public class ZlibInStream extends InStream {

	static final int defaultBufSize = 16384;

	public ZlibInStream(int bufSize_) {
		bufSize = bufSize_;
		b = new byte[bufSize];
		ptr = end = ptrOffset = 0;
		inflater = new java.util.zip.Inflater();
	}

	public ZlibInStream() {
		this(defaultBufSize);
	}

	public void setUnderlying(InStream is, int bytesIn_) {
		underlying = is;
		bytesIn = bytesIn_;
		ptr = end = 0;
	}

	public void reset() throws Exception {
		ptr = end = 0;
		if (underlying == null)
			return;

		while (bytesIn > 0) {
			decompress();
			end = 0; // throw away any data
		}
		underlying = null;
	}

	public int pos() {
		return ptrOffset + ptr;
	}

	protected int overrun(int itemSize, int nItems) throws Exception {
		if (itemSize > bufSize)
			throw new Exception("ZlibInStream overrun: max itemSize exceeded");
		if (underlying == null)
			throw new Exception("ZlibInStream overrun: no underlying stream");

		if (end - ptr != 0)
			System.arraycopy(b, ptr, b, 0, end - ptr);

		ptrOffset += ptr;
		end -= ptr;
		ptr = 0;

		while (end < itemSize) {
			decompress();
		}

		if (itemSize * nItems > end)
			nItems = end / itemSize;

		return nItems;
	}

	// decompress() calls the decompressor once. Note that this won't
	// necessarily generate any output data - it may just consume some input
	// data. Returns false if wait is false and we would block on the underlying
	// stream.

	private void decompress() throws Exception {
		try {
			underlying.check(1);
			int avail_in = underlying.getend() - underlying.getptr();
			if (avail_in > bytesIn)
				avail_in = bytesIn;

			if (inflater.needsInput()) {
				inflater.setInput(underlying.getbuf(), underlying.getptr(),
						avail_in);
			}

			int n = inflater.inflate(b, end, bufSize - end);

			end += n;
			if (inflater.needsInput()) {
				bytesIn -= avail_in;
				underlying.setptr(underlying.getptr() + avail_in);
			}
		} catch (java.util.zip.DataFormatException e) {
			throw new Exception("ZlibInStream: inflate failed");
		}
	}

	private InStream underlying;
	private int bufSize;
	private int ptrOffset;
	private java.util.zip.Inflater inflater;
	private int bytesIn;
}
